This bears further investigation...
We are down for the night in a well lit Walmart parking lot, first time out with my new solar panels. I realize Uni Solar said these panels produce electricity at low sun angles...but well after sunset?
The charge controller says it is sending 4+ Amps into the batteries. I guess at Walmart's expense.
And the charge controller appears to be telling the truth during the day.
I suppose it's possible, my chrge controller often shows an amp or more going in whilst under the adco cover on an overcast day.
If you park close to their parking lot large output lights you may find they give you a few amps too.
JohnH
Just to be nosey, are these the flexable surface mounted panels?? pc
Yes. A pair of Uni-Solar 136Watt panels. In a couple of weeks I'll have two 90Watt Global Solar flexible panels added.
I like to keep a clean roofline.
That is awesome Tom! I've tested our Uni-Solar panels in severe shading, fading sunlight, twilight, and they have always had open circuit voltage that was surprisingly close max. I didn't have any loads on them though, so it's nice to see that they function even under the conditions you describe... ^.^d if the Global Solar panels are even close to the Uni-Solar, it's going to make going off the grid much quieter for us ;D when my install is all said and done, we will have 476 watts of UniSolar panels and 360 watts of the Global Solar.
Don & Tys
Don,
Did you do anything different with your peel & stick panels to get them glued down?? pc
PC,
I haven't installed them yet, but the plan is to wash the roof, and then buff with a fine silicon free compound, wipe the roof with acetone before installing the panels and finally roll them out with a vinyl flooring roller. I may install a piece of aluminum trim on the leading edge screwed to the frame member or perhaps lap them with some eternabond tape.
Many projects in the works right now. Current plan: First is the hose and shore power reels along with relocating the noisy Progressive Industries EMS to the utility compartment if I can shoehorn it in ::) (Glendinning Hosemaster Model-M Model M - Glendinning Products, LLC. (http://www.glendinningprods.com/products/hosemaster/175-model-m), Shore Power Reel (Glendinning CRR-50 CRR-50 - Glendinning Products, LLC. (http://www.glendinningprods.com/products/cablemaster/cr-models/171-crr-50)). Next is the fridge install (Vitrifrigo DP2600iAC AC/DC 8.1 cu ft Marine Refrigerator Vitrifrigo DP2600iAC refrigerator ? 8.1 cu ft AC / DC powered for marine and RV (http://baymarinesupply.com/store/refrigeration/marine-rv-refrigerators-icemakers/vitrifrigo-dp2600iac-marine-rv-refrigerator.html)), inverter with the optional ARC50 remote and battery monitor (Magnum MSH-3012M Magnum Energy MSH3012M hybrid inverter and charger for marine, RV, and solar (http://baymarinesupply.com/store/electrical/chargers-inverters/magnum/magnum-msh3012m-marine-rv-inverter-charger.html)), the solar panels and the Midnight Solar Classic Charge controller and associated cabling, and some other stuff that escapes me now. I have all the parts for the projects listed above except the solar controller and cables.
Don
Don,
Are you going to be using Bill's shop with the new pit for all those projects?? ^.^d
Larry
Luckily non of those jobs need to get under coach for!!
I have ordered the pit from Amazon but it has not arrived yet!!
Johnh
John is right... None those projects would really benefit from a pit, But it sure would be handy for chasing down air leaks, flaky solenoid valves, and a hundred other maintenance items! ^.^d
Don
Bill's shop does not have pit. (John H was a "N SHOW")
I think what you are experiencing is normal. The solar panels on my house start to produce power before sunrise on a clear day and do not shut off until after sunset. Just a few watts, but it's something. If it's cloudy it takes longer before start up. You are not stealing anything from Walmart, the lamp consumes the same amount of power regardless of whether you are parked underneath.
Photons are photons. They don't know any different.
It's not the same as drafting on a bicycle in the Pelaton in the Tour de France.
Or the way birds draft by flying in formation (which, by the way, is a lot more complicated than it looks).
Why Birds Fly in a V Formation | Science/AAAS | News (http://news.sciencemag.org/biology/2014/01/why-birds-fly-v-formation)
best, paul
Something else about solar, there is a phenomenon called solar boost that can occur with a light overcast. The panel gets strong diffused light from several directions, then if the sun shines through a break in the clouds, the output is more than the sun alone. Total output on a day like that is less than on a clear day, so clear days are best. Humidity in the air can reduce output, and cool days are better than warm days.
"cool days are better than warm days"
You got that right. We're hopeful that today in El Centro, CA it will get to only 90 F
And we're promised a high of only 80F next week. Whooohoo!
best, paul
Just went to Amazon to check on getting the Uni-Solar 136Watt panels and there is a note there that these have been discontinued by the manufacturer. Interesting, no replacement or alternative mentioned.
The manufacturer, Uni-Solar is out of business, but their panels are still readily available. I found mine on EBay, 136 Watts x 2 for $326. I also have a pair of Global Solar panels, also flexible, 90 Watts x 2 for $350. These are physically smaller and better fit in the roof space now available.
Which is good for us, because when the company was still in business, these panels were selling for a whole lot more. List price for the 136 watt version was supposed to be over $600 apiece! Downside is warranty support, as in nada. The UniSolars were advertised as being able to be walked upon. The Global Solars... not so much. Different construction. Not as flexible and probably not as durable. But the size is right for the aft section of our coach's roof. I think it would be okay to walk on if covered by a rubber mat and maybe a thin piece of plywood over that. Where they are going on our coach is to the street side of the ladder so walking on them won't be routinely needed. I plan to tread lightly even on the UniSolars and mostly won't have to.
Don
What are the VOC (volts open circuit) and MPPV (maximum power point voltage) of Unisolar panels and Global panels. If they are not almost the same, the higher voltage ones will overpower the lower voltage ones and you will not get the rated output from all the panels.
I am quite interested in how well stick on panels stay attached over the years and how well they perform at higher temperatures.
My panels are not horizontal and are mounted with an air gap for cooling.
Wyatt,
I am interested to hear what your thoughts are about these panels. After a bit more research, it appears I either need to lose or add a 68 W panel to make my system work. I have the panels already and I can always find a use for any that don't get used on my 40' Conex box.
The STC (Standard Test Conditions) VOC (Voltage Open Circuit) and Vmp (Voltage at Pmax) of the panels;
UniSolar 136 Watt
VOC =46.2 V, Vmp =33.0 V
UniSolar 68 Watt
VOC 23.1 V, Vmp = 16.5
Global Solar
VOC 22.0 V, Vmp = 16.5
Don
Treat the 4 panels as two, 46 volt panels in parallel give 46 volts, 23 volt[or close to it] panels in series give 46 volts. Wire as such, and then parallel the two. You will probably need a mppt controller to handle the 46 volt input.
I currently have two UniSolar 136W panels in series and have two Global Solpr 90W panels soon to be added in series. My total open circuit voltage will be under the mppt controller's 150v max.
If I were to add more panels, I would parallel one or both identical pairs.
When the panels are wired in series it's not so important to "match" the panels. One of the major reasons I chose the Midnight Solar "Classic" which can handle up to 150vdc and convert that down to 12vdc for the battery bank.
There was a web page about installation of these "self-stick" Unisolar panels that mentioned a metal carrier but this was for a building installation. How they work on a fiberglass-roof RV should be very interesting. I have two of the smaller (70-watt) Unisolar panels that I originally planned to install on the curved sides of the roof of our U225 but I now think I'll stick them down for a walkway on the roof top. We also have two "standard" 240-watt 24vdc panels but might add a third (or another Unisolar).
I plan to mount my rigid panels with an air gap. It would be very interesting if someone could "shoot" their Unisolar panels with a Harbor Freight laser temperature gun when they're in the hot sun and post the temps.
I am still waffling about whether I'll make the panels so they tilt. As I get older I get far less excited about going up onto the roof. Actually, going up isn't so bad; it's the coming down fast and hard that makes me think twice about it.
Craig
Craig,
I installed two of the long self stick panels last year. Have not used them yet as coach is still in storage but they were very easy to install. Will post results when I use coach.
Keith
Last week, on a hot sunny afternoon, I did shoot the panels with an ir gun. They were running around 130 degrees while a black car was just under 160.
That's interesting!!! Now all we need is for someone to drive their rig around for a couple hours at 60mph (preferably with a headwind) and see how well they stay put. :P
Thanks, Tom :)
Craig
I've been trying to find something to do the buffing with. Everything I've looked at contains some sort of waxing agent which I am pretty sure I don't want for the installation of solar panels; either self-stick or tape.
Have you found the compound you plan to use, yet?
Craig
Meguiars professional products are silicone free and body shop/paint shop safe according to their website and the automotive paint supply store where I bought mine. I don't believe that the cutting compound available in many grits from superfine to fast cutting has any waxing agent, but since I will be doing a acetone wipe down, I am not too worried about it. Autobody repair and paint shops generally don't want silicone anywhere near their paint booths for obvious reasons!
Don
Thanks, Don. I figured it would be a Meguires product but none of the auto stores here (small town) had anything that looked like what I needed. Another addition to the Amazon shopping list...
Craig
I like the idea that Unisolar panels provide more power then other panels when the sun is low in the sky. I do not like the price. I recently bought 1200 watts at less than $1.00 per watt.
You will need to pair (in series) the Unisolar 68 watt and the Global panels to match the voltage of the Unisolar 136 watt.
You will also require a solar charge controller which can accommodate at least 50 VOC and not all controllers can do this, so check the controller you are buying.
If you have an odd number of the lower voltage panels, you could run separate wires down to the outside fridge door and use the power to charge other 6 or 12 volt batteries. I have done this with three 55watt panels and run the ceiling fan or charge spare batteries (flooded/sealed 6v or 12v or even 1.5volt AA). It is possible to charge 6 volt batteries as long as you are not charging with more amps than the battery can accommodate. Matching panel and battery voltage does not matter when you connect the panels directly to a battery (no controller). The panels will work at battery voltage and will never provide more than "short circuit amps". Incidentally, they will not provide their rated wattage because the panel voltage is below VMP.
If you want to series all your panels to bring high voltage (circa 150v) off the roof be aware of that a short due to insulation wear will result in welding things together with no end until the sun goes down.
Also note that, as the input voltage to a solar controller goes up, the efficiency of the controller goes down. The big plus side is that as the voltage goes up, the line loss goes down and you can use lighter wires.
I have an odd number of 28 VMP panels so did not pair them.
Well, since you ask...I am almost back home now, from Los Angeles to north of San Francisco and back, often at 60-65 mph with a variety of winds. The panels haven't budged.
Here's a quick update on too good to be true.
It was too good, and not true.
It appears my charge controller's current monitor needed a few cycles to find it's limits. It was consistently reading 4 Amps too high for the first week. Now it is reading correctly, including zero Amps after dark.
As an aside, I really like having the Tri-Metric 2020 on board. I now know ihe coach is using 2A at night with everything off except the refrigerator. I now know the Prosine inverter is a power hog even with the TV off. And I know for real how power hungry my fluorescent lamps are compared to the LEDs.
Having fun here.